Exploring and producing natural gas and crude oil has a whole variety of hazards. Flammable gas will be continually present during the processes involved requiring that plant and personnel be monitored for risk levels. Gas well sites are hazardous in a number of ways to both site workers and adjacent properties. Critical Leases are well sites that include a (significant) risk of escape of poisonous or explosive vapours “On Lease”, typically in specific “critical zones” (also known as Hot Zones) separate from a work area or “Job Shack” from which workers monitor the entire well site. “Downwind” from such critical leases, poisonous vapours (an indicator of which is the combustion product generated during flaring activities) threaten nearby humans and livestock to different extents influenced by wind direction and speed. Geologists provide information respecting the location of “sour zones” such that for new wells Drilling Rig operators in cooperation with a Drilling Consultant will determine where to place Stationary Monitoring Units (SMUs) both On Lease and Downwind. Similarly, during the production phase of an existing well, Service Rig operators in cooperation with a Drilling Consultant will determine how to setup “forehead monitoring” and downwind equipment.
The Lower Explosive Limit (LEL) of a flammable gas is the minimum concentration of that gas, at normal ambient conditions, at which it will burn if there is a source of ignition present. At a concentration below the LEL, the gas will not burn. Gas detectors for flammable gases are typically calibrated in the range 0–100% LEL. The actual concentration of the LEL varies from one gas to another. It has become industry practice that workers not enter spaces where the concentration of a gas exceeds 20% of the LEL because the concentration will vary at different places and it is likely that there will be pockets of gas that will exceed the LEL creating risk of explosion such that it is important to monitor LEL levels on such work sites. Further, various regulatory bodies impose monitoring requirements on lease requiring well site operators to track the percentage of the LEL of various flammable gases present on site.
Conventional technologies for “On Lease” monitoring provide relatively local audible and visual alarms that alert workers in the Job Shack, who must then “suit up” in chemical proof garments before approaching the hot zones to determine which of a plurality of such zones has entered alarm condition. Disadvantageously, the need to suit up creates delay in handling an emergency while the need to approach a hot zone creates (avoidable) risk to the worker. Conventional technologies for Downwind monitoring rely on a plurality of independent monitoring stations that may each communicate directly with a central monitoring station, such that a plurality of modems are deployed at significant expense for marginal benefit in redundancy.
Supervisory Control and Data Acquisition (“SCADA”) systems have been used in industry to monitor and control plant status at the same time as providing records of that status or “logging” functionality. SCADA systems usually interface to the subject equipment in the plant using some form of programmable logic control (“PLC”) device (useful stand-alone or in conjunction with a system to automate the monitoring and control of an industrial plant). As the name indicates, SCADA is not a full control system, but operates in a supervisory manner providing alarms that alert operators who then take manual control of the problematic equipment. SCADA is implemented as software positioned on top of the equipment to which it is interfaced using any suitable commercial hardware module. Systems similar to SCADA systems are often referred to as Distributed Control Systems (DCS), usually located within a confined area such that communication can be on a local area network (LAN) that is reliable and high speed. However, wireless Remote Terminal Units (“RTUs”) can also be used to transfer to different sites the data accessed from equipment being monitored and controlled. Typically the data acquisition is by an RTU including a PLC to receive the various inputs continuously delivered at high transfer rates by equipment hardwired to the RTU. In modern SCADA systems a host or master terminal unit then periodically scans or polls one or more wireless RTUs to gather the input data so acquired. This data can be analog or digital information gathered by monitoring sensors (e.g. flowmeter, ammeter), or data that controls equipment (e.g. relays, valves, motors) automatically or with operator intervention. Conventional SCADA systems use the RTU as a high reliability buffer and relay utility that can receive relatively large volumes of data and forward it as needed for processing by a host or master unit, the benefit of which is continuous logs that may be processed and re-processed by a host in different ways to extract information for different purposes as required. As host processing power has increased the buffering functionality of the RTU has become less important making it possible for systems (such as SMART described below) to have a plurality of sensors transmitting directly to the host without an RTU. Data whether buffered or directly transferred may be processed for a variety of purposes by a SCADA system, for example, the data is typically processed by the host to detect alarm conditions, and if an alarm is present, an alarm related interface can display notice of the condition causing the alarm. Conventional RTUs forwarding sensor traffic via RF to a master unit at a plant control center typically rely on relay towers or large antenna suitable for high power transmission, which for rapid deployment applications in remote locations (e.g. undeveloped regions of the Arctic) makes them either unavailable (e.g. no supporting infrastructure) or uneconomical (e.g. too expensive to justify transport) to implement for short-term, including emergency installations.
Although no patented prior art is known to the applicant, a number of companies providing portions of the above conventional solutions have been identified, including BW Technologies whose detection and analysis technology focus is efficiency rather than safety. The Rig Rat II is a microprocessor based gas detection apparatus detecting for combustibles, toxics, and/or oxygen hazards On Lease. With independent wireless radio signal transmission via coded radio channels the independently powered, solar capable detectors are easily moved. Rig Rat II is modular in design with plug-in ports for remote sensors, remote alarms, relays, and solar power. Installation costs are reduced by the use of wireless technologies, thereby eliminating cabling, wiring, conduit and trenching. Although the Rig Rat II is intrinsically safe, permitting it to be deployed inside hot zones, it has no ability to transfer data to remote locations, through the InterNet or otherwise.
Further, SAT-TEL Corporation provides its SMART system for Downwind applications working with Iroc Systems Corp. Using Sat-Tel's SMART (Satellite Monitored Automated Reporting Terminal) monitoring technology assets are easily managed regardless of their geographic location. Sat-Tel configures existing technology to provide real-time monitoring via satellite communication. Unlike Rig Rat II, SMART is not intrinsically safe and cannot be deployed On Lease in hot zones. Like Rig Rat II, SMART units are self sufficiently powered by a 12V car battery charged via solar panel, tracking it's own power status. Designed to monitor four sensor inputs, such as humidity, weight, and wind speed. The Data Logger element of the SMART system takes samples at industry standard five second intervals, averaged every minute, and reported every fifteen minutes. Data is sent to Sat-Tel's call center via wireless fixed site satellite modem. Sat-Tel's SMART technology is specifically designed for H2S ppm, SO2 ppb gas detection and is for use in only the downwind monitoring application. Further, SMART is based on proprietary MSAT communications links that support highly directional, one-way, data transmission only, making it necessary for operators to carry separate voice communication devices. SMART is characterized by unnecessary multiple redundancies in both data collection and transmission, with each unit requiring a separate MSAT satellite transponder and IP address (i.e. for each sensor station) multiplying communication costs. MSAT's reliance on static IP addressing disadvantageously creates a security risk, while its one-way configuration disadvantageously prevents remotely transmitting instructions to the equipment on a remote site. Further MSAT is not suitable for the transmission of Motion JPEG video images.
U.S. Patent Application 2001/0040509 (“509”) filed by Dungan apparently teaches an apparatus and method for wireless gas monitoring, which purportedly improves over older Remote Terminal Unit (“RTU”) based technology by allegedly “integrating” the transmitter in the same housing as the gas sensor or sensor array. Although not limited to satellite transmissions, in the 509 application at FIG. 4 one embodiment is disclosed according to which Low Earth Orbit (“LEO”) satellite means are used to relay a signal from a Monitoring Station (14) adjacent a hazardous location to a remote Master Station (118) for further handling. Since the stated problem with the prior art RTUs is the need for “large” dish antennas having “higher gain”, making it attractive to eliminate the use of “bulky and expensive” RTUs the LEO system operating at low altitude within relatively easy reach of less powerful transmitters is essential to the operation of the 509 system. Disadvantageously the LEO approach suffers from a “small footprint” limitation inherent in this low-power technology resulting in restrictions on the areas in which it may be deployed for remote access. The one-to-one transmitter-to-sensor correspondence of the 509 system is also very similar to SMART by Sat-Tel/IROC such that including the transmitter in the sensor housing is characterized by unnecessary multiple redundancies in high-powered data transmission whenever a plurality of sensors are deployed. Both 509 and SMART implement a “stand-alone” independent sensor & transmitter combination according to which each sensor or monitoring station sends data to a remote “master” (whether on-site or off-site respecting the gas detection location) that responds in some manner to the information carried in such data. Although the amount of data so transmitted can vary (e.g. normal vs. alarm mode) both 509 and SMART necessitate significant overhead in air-time for the transmission of data, when used in remote sensing applications disadvantageously resulting in the consumption of expensive (high-powered, long-distance) bandwidth during each transmission from each sensor station. Aggravating the above situation is the commensurate consumption of extra IP-addresses by the unnecessary multiple redundancy of the configuration of the 509 and SMART systems, dictating one IP address per sensor station, when equivalent information about each station may now be transmitted without consuming one IP-address per station. 509 further teaches at para. 70 a large number of very rapid sensor signal transmissions such that no averaging or pre-processing at the sensor station is permitted since “each monitoring device 14 will very rapidly transmit its readings to an output center. Because these transmissions occur so often, there is insufficient time for data readings to accumulate between transmissions.”, which failure to pre-process data from sensor stations further increases the burden on the communications system and budget. It is therefore desirable to both process and transmit sensor data in a manner that reduces the amount of data sent and the communication uplink usage time—without compromising the quality or completeness of the information required to achieve the system objectives of location targeted early warning, nature and direction of gas escape, and sufficient records to comply with local regulations.
A common problem with all gas sensors, especially those operating at remote sites, is anomalous readings (false alarms) resulting from substantial shifts in temperature, wind speed, humidity or other atmospheric conditions that influence the (best) interpretation of the raw signal from sensors. It is desirable to compensate for such changes in atmospheric conditions (resulting for example from forest fires and fast moving cold fronts—common in mountainous terrain) by adjusting the interpretation of sensor data, before it is processed, by averaging unadjusted data into other data that would be distorted by its inclusion.
All known conventional well-site monitoring systems are wireless, use a 19.2 kbps data communication IP connection, and are independently powered, but are limited to either On Lease or Downwind applications and use relatively expensive and inflexible technologies. There is a need for a relatively simple and affordable integrated system that may be used in a variety of applications to communicate remotely using the InterNet efficiently transferring information regarding several sensors via a single IP address. None of the known conventional technologies temperature compensates sensor data. None of the known conventional technologies integrates video security functionality with its gas monitoring.
Schlumberger's new product currently known as “InterACT” is described as providing “secure, real-time, Web-based exploration, development and production data.” InterACT allegedly permits authorized team members located anywhere around the globe to view data in the course of collaborative decision making. It is further described as suitable for: Remote data acquisition and delivery; Two-way communication and distribution of real-time drilling, wireline, stimulation and production information; Selective sharing of data among several parties; Remote monitoring of well-site operations; and Supervisory control of remote assets. Although limited information is currently available respecting how it allegedly achieves the above functionality, it is believed that in the Remote monitoring application the InterACT system uses a group of local sensor stations that transmit via RF to a relay device that forwards data via FTP to a server off-site for viewing by users. Disadvantageously, when the InterACT monitoring system is setup in an area having access to both (less expensive) cellular service and (more reliable) satellite service, the communications element has no means to auto-detect, auto-select, and auto-switch between satellite and cellular communication modes whenever and as it becomes appropriate to do so. The InterACT system also fails to provide for dual voice-IP usage of the communication system.
U.S. Patent Application 20020155622 (“622”) by Slater et al. purports to teach a “toxic gas monitoring system” based on individual (slave) radio-paging units worn by workers in hazardous areas. According to one embodiment the pagers receive an alarm signal from a centrally located (master) sensor unit and transmitter, which signal warns all workers of the presence of gas in the subject work space. According to another embodiment the pagers each include a gas sensor, are self-identifying, and have 2-way communication capability including a “panic button” such that any pager can trigger the entire system into alarm. According to a third embodiment the 2-way pagers and their centrally located (master) sensor unit each communicate with an external resource such as a rescue crew. 622 contemplates a group of such systems operating in “repair cells” to cover a large industrial facility. There is no indication in 622 that much more than simple signals are exchanged over limited distances to trigger events such as alarms that alert operators and supporting resources to the presence of gas.
Industrial facilities commonly use the popular HART® protocol for which a wide array of reliable and affordable peripheral devices have been developed over years. The HART® Multiplexor system facilitates the gathering of HART® protocol data in order to permit asset management by those who operate and maintain a plant. Data is gathered via a plug-in modular unit housed on a field termination board. The multiplexor and fieldgates enable the use of a PC for the remote monitoring, remote diagnosis and remote configuration of connected HART® sensors and actuators, via telephone lines (analogue and ISDN), Ethernet TCP/IP, or mobile communications (e.g. GSM). Communication with the field device is a sub-layered service that does not interrupt the measurement signal, such that data access procedures have no influence on the measured value processing performed by associated process control and instrument systems. Consequently, it is desirable for remote access applications to have available means for connecting “off the shelf” sensors and other peripherals from which data may be gathered and which connection employs a popular and reliable industry standard.